Satellite diversity

ABSTRACT

A wireless communication system includes frequency reuse between terminals in common coverage regions using a multiple satellite architecture with spatial diversity. Different terminals may be associated with different ones of the satellites such that a common frequency can be reused by the different terminals. A gateway may communicate with a first satellite using a feeder beam having an overlapping geographic coverage region with a user beam used for communication between a set of user terminals and a second satellite. Spatial diversity is provided between the satellites, and the feeder beam and the user beam operate at common frequencies within the overlapping coverage region. In this manner, the bandwidth of both satellites at the common coverage region is used to increase the available capacity.

CLAIM OF PRIORITY

The present application is a divisional application of U.S. patentapplication Ser. No. 15/221,273, entitled “Satellite Diversity,” byKirby Chung, filed Jul. 27, 2016, which claims priority from U.S.Provisional Patent Application No. 62/286,144, entitled “SatelliteDiversity,” by Kirby Chung, filed Jan. 22, 2016, incorporated byreference herein in its entirety.

BACKGROUND OF THE INVENTION

The present disclosure relates to technology for wireless communicationsystems.

Wireless communication systems typically include a communicationplatform such as a dedicated terrestrial antenna, airborne platform, orcommunications spacecraft such as a satellite. Such platforms typicallyoperate within regulations that allocate at least one operatingfrequency bandwidth for a particular communications service and specify,among other things, a maximum signal power spectral density (PSD) ofcommunications signals radiated to the ground, etc. A growing marketexists for provision of high data rate communication services toindividual consumers and small businesses which may be underserved by orunable to afford conventional terrestrial services. To advantageouslyprovide high data rate communication services to such users, acommunications platform must (1) provide a high PSD so as to enable theuse of low cost user terminals, and (2) efficiently use the licensedbandwidth so as to maximize the communications throughput for aparticular licensed bandwidth.

Typically, frequency reuse plans are developed prior to design anddeployment of a communications system in order to service the projectedneeds of the system. Frequencies are often reused between geographicallyseparated terminals. For example, highly directional antennas may beused to create multiple gateway and user beams. Frequencies may bere-used between the gateway beams and user beams where the beams andterminals within the beams are geographically separated with adequatespatial isolation. Additionally, frequencies may be reused between userbeams where the user beams are geographically separated and may bereused between gateway beams where the gateway beams are geographicallyisolated. Because of the requirements of spatial isolation between theterminals, capacity may be limited.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram describing an example of a wirelesscommunications system.

FIG. 2 is a map describing the placement of gateways and user beams andan example of a frequency reuse plan.

FIG. 3A is a diagram describing an example of unique combinations offrequency and polarization that may be used in a frequency reuse plan.

FIG. 3B is a diagram describing the frequency assignments for uplinksand downlinks using the frequency/polarization combinations in FIG. 3A.

FIG. 4 is a diagram describing another example of unique combinations offrequency and polarization that may be used in a frequency reuse plan.

FIG. 5 is a simplified block diagram describing a wirelesscommunications system including a multi-satellite architecture inaccordance with one embodiment.

FIG. 6 is a table describing an example of frequency reuse within acommon coverage region in accordance with one embodiment.

FIG. 7 is a flowchart describing a process of reusing frequencies withina common coverage region by a multi-satellite system in accordance withone embodiment.

FIG. 8 is a flowchart describing a process of communication with agateway and one or more user terminals using a multi-satellite system inaccordance with one embodiment.

FIG. 9A is a simplified block diagram of the forward payload of asatellite providing a feeder beam in accordance with one embodiment.

FIG. 9B is a simplified block diagram of the return payload of asatellite providing a feeder beam in accordance with one embodiment.

FIG. 10A is a simplified block diagram of the forward payload of asatellite providing a user beam in accordance with one embodiment.

FIG. 10B is a simplified block diagram of the return payload of asatellite providing a user beam in accordance with one embodiment.

FIG. 11 is a simplified block diagram describing a wirelesscommunications system including multiple satellites that service bothgateways and user terminals in a common coverage region.

FIG. 12 is a flowchart describing a process of reusing frequencieswithin a common coverage region by satellites that service both gatewaysand user terminals in a common coverage region in accordance with oneembodiment.

FIG. 13 is a flowchart describing a process of communication betweengateways and user terminals by satellites that service both gateways anduser terminals in a common coverage region in accordance with oneembodiment.

FIG. 14 is a simplified block diagram describing a wirelesscommunications system including multiple satellites that providecommunication between user terminals.

DETAILED DESCRIPTION

The disclosed technology is directed to bandwidth allocations inwireless communication systems that provide frequency re-use. Wirelesscommunication systems are disclosed including multiple satellites thatprovide spot beams to cover a geographic service region. The spot beamsare associated with coverage regions within the overall geographicservice region. The spot beams may be associated with one or moregateway terminals and/or one or more user terminals.

Frequency re-use is employed such that unique combinations of frequencyand polarization are associated with beams provided by two or moresatellites to an overlapping coverage region. In one example, a firstsatellite provides a feeder beam having a feeder beam coverage area thatat least partially overlaps with a user beam coverage area associatedwith a user beam provided by a second satellite. Spatial diversity isprovided between the two satellites to permit frequency re-use for theoverlapping feeder and user beams. Inter-satellite communication linksare provided to transmit data between the two satellites. In thismanner, a gateway can communicate with the first satellite using thesame frequencies with which a user terminal communicates with the secondsatellite. Communication between the gateway and user terminals isfacilitated by the inter-satellite communication links. With such anapproach, two or more satellites provide coverage to a common serviceregion using the same frequencies such that system capacity can beincreased in the common coverage region by the sum of the capabilitiesof each satellite in that region. Additional satellites in addition tothe first and second satellite can be employed to provide additionaluser beams to the common coverage area to thereby further increase theavailable capacity in the area.

In one example, the first satellite receives uplink signals in thefeeder beam from a gateway in the common coverage area using a firstcombination of frequency band and antenna polarization (“F/Pcombination”) and provides downlink signals to the gateway using asecond F/P combination. The second satellite receives uplink signals ina user beam from a user terminal in the common coverage area using thefirst F/P combination and provides downlink signals to the user terminalusing the second F/P combination. Alternately, the second satellite mayreceive the uplink signals using the second F/P combination and providethe downlink signals using the first F/P combination.

Data is received at the first satellite from an uplink signal of thefeeder beam using the first F/P combination. The first satellitetransmits the data using an inter-satellite communication link to thesecond satellite. The inter-satellite communication link may use thesame or different frequencies than the uplinks and downlinks. The secondsatellite transmits the data in a downlink signal of the user beam tothe common coverage area.

In a similar manner, the multiple satellites may provide bi-directionalcommunication between two user terminals using the same frequencies. Forexample, data can be received at the first satellite in an uplink signalof first user beam from a first user terminal using a first F/Pcombination. The first satellite transmits the data to the secondsatellite using an inter-satellite communication link. Similarly, datacan be received at the second satellite in an uplink signal of a seconduser beam from a second user terminal using the first F/P combination.The second satellite transmits the data from the second user terminal tothe first satellite. The first satellite transmits the data from thesecond user terminal in a downlink signal to the first user terminalusing a second F/P combination and the second satellite transmits thedata from the first user terminal in a downlink signal to the seconduser terminal using the first F/P combination. Alternately, the downlinkfrom the second satellite may use the first F/P combination and theuplink use the second F/P combination.

In one embodiment, each satellite is a dedicated gateway satellite thatprovides feeder beams for one or more gateways or a dedicated userterminal satellite that provides user beams for sets of user terminals.Access functions can be separated between the satellites to allow systemoptimizations for capacity or reach-back to distances between userterminals and gateways that are larger than one satellite may perform toavoid so-called double-hop.

In another embodiment, the individual satellites may be associated withboth gateways and user terminals. For example, the first satellite canreceive uplink signals from a gateway in the common coverage area usinga first F/P combination and provide downlink signals to the gatewayusing a second F/P combination. The first satellite can receive uplinksignals from a first set of user terminals in the common coverage areausing a third F/P combination and provide downlink signals to the firstset using a fourth F/P combination. The second satellite can receiveuplink signals from a second set of user terminals in the commoncoverage area using the first F/P combination and provide downlinksignals to the second set of user terminals using the second F/Pcombination. The second satellite can receive uplink signals from asecond gateway in the common coverage area using the third F/Pcombination and provide downlink signals to the second gateway using thefourth F/P combination. Variations of the described re-frequency re-usesmay be employed whereby two terminals in a common coverage area may usethe same frequencies without interference by communicating withdifferent satellites having spatial separation.

FIG. 1 depicts a simplified diagram of a portion of a typical wirelesscommunications environment. In the example of FIG. 1, a communicationsplatform includes a satellite 120 forming part of a wirelesscommunications network 100. Satellite 120 may be located, for example,at a geostationary or non-geostationary orbital location. Satellite 120may be communicatively coupled, via at least one feeder link antenna, toat least one gateway 110 and, via at least one user link antenna to aplurality of user terminals 130. The term user terminals 130 may be usedto refer to a single user terminal or user terminals such as userterminals 130-1, 130-2, 130-3 collectively. A user terminal is adaptedfor communication with a wireless communication platform such assatellite 120. User terminals may include fixed and mobile userterminals including, but not limited to, a cellular telephone, wirelesshandset, a wireless modem, a data transceiver, a paging or positiondetermination receive, or mobile radio-telephone. A user terminal may behand-held, portable (including vehicle-mounted installations for cars,trucks, boats, trains, planes, etc.) or fixed as desired. A userterminal may be referred to as a wireless communication device, a mobilestation, a mobile wireless unit, a user, a subscriber, or a mobiledevice.

The at least one gateway 110 may be coupled to a network such as, forexample, the Internet, terrestrial public switched telephone network,mobile telephone network, etc. A gateway 110 and the satellite 120communicate over a feeder link 113, which has both a forward uplink 114and a return downlink 115. Feeder link 113 may operate for example, inan assigned or allocated frequency band (e.g, between 17 and 80 GHz).Although a single gateway is shown, typical implementations will includemany gateways, such as five, ten, or more. Each gateway may utilize itsown gateway beam, although more than one gateway can be positionedwithin a beam.

User terminals 130 and the satellite 120 communicate over user links 117that have both a forward downlink 118 and a return uplink 119. Threeuser terminals with three user links 117-1-117-3 are shown by way ofexample. Typical implementations will include many user terminals.Moreover, many user terminals may be located within the geographiccoverage area of a single user beam. Many user beams may be included invarious implementations. For example, fifty, sixty or more (or less)user beams may be used to generate a service region. User link 117 mayoperate in an assigned frequency band that is different than or the sameas the frequency assigned to feeder link 113. For example, the userlinks may operate in the same assigned frequency band as the gateway,such as where the gateway is located in a coverage area spatiallyseparated from the coverage areas of the user beam or user beams forwhich the frequency is re-used. In other examples, one or more gatewaysmay be located in the same coverage area as a user beam coverage area.The gateway may share the available frequency spectrum.

A spacecraft antenna subsystem may provide an antenna beam patternwherein an entire service region is covered using the availablebandwidth at a single time using a single beam. In another example,however, multiple satellite antenna beams (or cells) are provided, eachof which can serve a substantially distinct cell within an overallservice region. In one embodiment, satellite 120 is a multi-beamspacecraft having an antenna subsystem for providing a grid of antennaspot beams. The shape of the grid in turn defines a service region. Thegrid of individual spot beams (user beams) divides an overall serviceregion into a number of smaller cells. For example, U.S. patentapplication Ser. No. 11/467,490 describes a pattern of 135 spot beamscovering the continental United States (CONUS), Hawaii, Alaska, andPuerto Rico. It is noted that a service region may be defined in anymanner to cover any desired geographic location. In one embodiment, theantenna subsystem includes a phased array antenna, a direct radiatingantenna, or a multi-feed fed reflector.

Dividing the overall service region into a plurality of smaller cellspermits frequency reuse, thereby substantially increasing the bandwidthutilization efficiency. In some examples of frequency reuse, a totalbandwidth allocated to the downlink is divided into separatenon-overlapping blocks for the forward downlink 118 and the returndownlink 115. Similarly, the total bandwidth allocated to the uplink isdivided into separate non-overlapping blocks for the forward uplink 114and the return uplink 119.

In other examples, some or all of the allocated bandwidth is reused bythe gateway(s) 110, thereby providing for simultaneous operation of atleast a portion of the feeder link 113 and a portion of the user link117 at common frequencies. More specifically, forward uplink 114 andreturn uplink 119 may reuse the same frequency and forward downlink 118and return downlink 115 may reuse the same frequency. Simultaneousoperation of the feeder link 113 and the user link 117 at commonfrequencies means that the gateway(s) 110 may reuse any part of thetotal bandwidth allocated to the user antenna beams. This may beaccomplished in various ways.

The architecture of FIG. 1 is provided by way of example and notlimitation. Embodiments of the disclosed technology may be practicedusing numerous types of implementations. For example, somecommunications systems may only include a single terminal type, such asuser terminals that communicate with one another. In such systems,gateways may not be used.

FIG. 2 depicts a specific example of an antenna coverage pattern thatprovides for spatial separation between the gateway(s) 110 in gatewaybeams 123 and a service region 121 of user beams 142 to enablenon-interfering use of the same frequency by the gateway(s) 110 and userterminals 130. FIG. 2 is provided by way of example only, as it will beapparent that any number and type of coverage patterns may be used inaccordance with embodiments of the disclosed technology. As shown inFIG. 2, the service region 121 is defined as the footprint made by aplurality of user beams 142. The term user beam 142 may be used to referto a single user beam or multiple user beams such as 142-1 to 142-16collectively. These user beams correspond to the geographic coveragearea serviced by a particular user link 117. A user terminal 130 locatedwithin the footprint of any of the user beams 142 may be communicativelycoupled over a user link 117 to spacecraft 120. Each gateway 110 islocated in a gateway beam 123. Spacecraft 120 may be communicativelycoupled over feeder link 113 to any one of the gateways 110. Eachgateway 110 may also be proximate to, and communicatively coupled with,a high speed Internet backbone access point. Each of the gateway beamsis substantially spatially isolated from the service region 121. Becauseof this spatial isolation, the user link 117 is operable at the samefrequency(ies) as the feeder link 113. Moreover, the frequency bandcommon to both the feeder link 113 and the user link 117 may encompasssubstantially all of the allocated bandwidth.

Typically, frequency reuse by two or more user beams 142 may be used butthe beams require spatial isolation or different polarizations. Forexample, any two user beams may employ the same frequency without regardto antenna polarization where the two user beams are spatially isolated(i.e., not adjacent or overlapping). Adjacent user beams may use acommon frequency where each adjacent user beam operates at a differentantenna polarization. Frequency re-use within a plurality of user beams142 may also use, for example, what is referred to as a “color” re-useplan.

FIG. 3A is a diagram showing a frequency band allocation in acommunications system for a set of uplink signals and downlink signals.A specific example is described of a color re-use plan. Each colorrepresents a unique combination of frequency band and antennapolarization. In this example, color ‘a’ represents a first sub-band(29.50 GHz-29.75 GHz) of an allocated uplink frequency band (29.50GHz-30.00 GHz) with a right-hand circular polarization (RHCP). Color ‘b’represents a second sub-band (29.75 GHz-30.00 GHz) of the allocateduplink frequency band with RHCP. Color ‘c’ represents the first sub-bandof the allocated uplink frequency band with a left-hand circularpolarization (LHCP). Color ‘d’ represents the second sub-band of theallocated uplink frequency band with LHCP.

Similarly for the downlink, color ‘A’ represents a first sub-band (19.70GHz-19.95 GHz) of the allocated downlink frequency band (19.70 GHz-20.20GHz) with RHCP. Color ‘B’ represents a second sub-band (19.95 GHz-20.20GHz) of the allocated downlink frequency band with RHCP. Color ‘C’represents the first sub-band of the allocated downlink frequency bandwith LHCP. Color ‘D’ represents the second sub-band of the allocateddownlink frequency band with LHCP. The colors may include otherallocations of the frequency band and polarization.

FIG. 3B is a table showing an example of an allocation of the uniquefrequency/polarization combinations to the uplink and downlink signalsfor feeder and user beams. The forward uplinks and return uplinks sharethe 29.50 GHz-30.00 GHz spectrum such that colors a-d can be re-used.Colors ‘a’ and ‘c’ in the 29.50 GHz to 29.75 GHz band are colorsassigned to spot beams for both forward uplinks and return uplinks.Colors ‘b’ and ‘d’ in the 29.75 GHz to 30.00 GHz band are colorsassigned to spot beams for both forward uplinks and return uplinks. Theforward uplinks are used for gateway to satellite communication in oneexample. If the gateways are geographically isolated all of the colors‘a’-‘d’ may be re-used by all of the gateways. If a gateway beam isadjacent to another gateway beam or is adjacent to a user beam, theassignments may be made in such a way that the gateway beam does not usethe same color for any beam to which it is adjacent. The return uplinksare used for user terminal to satellite communication in one example.Each user spot beam may be assigned one dedicated color ‘a’-‘d’, forexample, as shown in FIG. 2. The assignments may be made such thatadjacent user beams do not share the same color.

Similarly, the forward downlinks and return downlinks share the 19.70GHz-20.20 GHz spectrum such that colors A-D can be re-used between theforward and return downlinks. Colors ‘A’ and ‘C’ in the 19.70 GHz to19.95 GHz band are colors assigned to spot beams for both forwarddownlinks (e.g., user terminals) and return downlinks (e.g., gateways)as well as colors ‘B’ and ‘C’ in the 19.975 GHz to 20.20 GHz band. Thereturn downlinks are used for satellite to gateway communication in oneexample. If the gateways are geographically isolated all of the colors‘A’-‘D’ may be re-used by all of the gateways. If a gateway beam isadjacent to another gateway beam or is adjacent to a user beam, theassignments may be made in such a way that the gateway beam does not usethe same color for any beam to which it is adjacent. The forwarddownlinks are used for satellite to user terminal communication in oneexample. Each user spot beam may be assigned one dedicated color‘A’-‘D’, for example, as shown in FIG. 2. The assignments may be madesuch that adjacent user beams do not share the same color.

Typically, an assignment of colors to user beams 142 provides that twoadjacent user beams do not share both a common frequency and a commonpolarization for use at a given time. In the disclosed example, adjacentbeams do not share the same color such that the unique combinations offrequency and polarization are not shared between beams. In FIG. 2, anexample is shown where each gateway beam is spatially separated fromeach of the user beams as well as the other gateway beams. Accordingly,each gateway may operate in its feeder beam at every color withoutinterfering with communication in the other user beams and gateway beam.The individual user beams operate at one of the four available colorssuch that no two adjacent user beams share the same color. In thismanner, frequency reuse between user beams does not lead to interferencewhere the coverage areas at least partially overlap.

It is noted that in FIG. 2 only the uppercase lettering designating thedownlink signals in the feeder and user beams is shown for simplicity.Similarly, each beam operates at the frequency/polarization combinationfor uplink signals at the corresponding lowercase color. Moreover, afour color re-use plan is provided as an example only as any number ofcolors may be used in a given frequency re-use plan. For example, threecolor re-use plans are common whereby a first color represents a firstfrequency band and first polarization, a second color represents asecond frequency band and the first polarization, and a third colorrepresents the entire frequency band at the second polarization. For afurther discussion of frequency re-use, refer to U.S. Pat. No.7,793,070, entitled “Multi-Beam Satellite Network to Maximize BandwidthUtilization.” It is noted that the service region and antenna pattern ofFIG. 2 is a simplified example. The disclosed concepts may be practicedin any geographic service region. Numerous examples and implementationsmay be practiced within the scope of the disclosure.

Another example is shown in FIG. 4 where some of the gateways areadjacent to or overlapping with one or more user beams. For example,gateway beam 123-4 is adjacent to a user beam 142-9 and gateway beam123-2 is overlapping or adjacent to user beams 142-1, 142-2, and 142-5.Because user beams are adjacent to the gateway beams, the gateway beamsoperate at a subset of the colors in the allocated frequency band toavoid interference. Specifically in this example, user beam 142-9 isallocated the frequency/polarization combination ‘A.’ Accordingly,gateway beam 123-4 is assigned the remaining colors ‘B,’ ‘C,’ and ‘D’without assignment of color A. Gateway beam 123-4 will operate at thereduced frequency allocation to avoid interference in the color ‘A’frequency band in user beam 142-9. User beam 142-1 is allocated color‘A’, user beam 142-5 is allocated color ‘C’ and user beam 142-2 isallocated color ‘B.’ Accordingly, gateway beam 123-2 is assigned color‘D’ only without assignment of colors ‘A,’ ‘B,’ and ‘C’ to avoidinterference in the other user beams.

As FIG. 4 illustrates, typical frequency re-use plans do not permitfrequency re-use between gateway beams and user beams that are adjacentand/or overlapping. For example, potential interference at channelswithin the colors A, B, and C of adjacent spot beams 142-1, 142-2, and142-5 generally leads to allocations of a gateway beam such as beam123-2 at reduced bandwidths only within color D.

In accordance with one embodiment, frequency reuse is provided betweenterminals in common coverage regions using a multiple satellitearchitecture with spatial diversity. Different terminals may beassociated with different ones of the satellites such that a commonfrequency can be reused by the different terminals. For example, agateway may communicate with a first satellite using a feeder beamhaving a geographic coverage region that overlaps the geographiccoverage region of a user beam that a set of user terminals use tocommunicate with a second satellite. Because of spatial diversitybetween the satellites, the feeder beam and the user beam may operate atcommon frequencies within the overlapping coverage region. In thismanner, the bandwidth of both satellites at the common coverage regioncan be used to double the available capacity.

FIG. 5 is a simplified block diagram showing a multiple satellitearchitecture that permits frequency reuse within a common coverageregion according to one embodiment. FIG. 5 shows two satellites 120-x(SATX) and 120-y (SATY), gateway 110-x, and user terminal 130-y, similarto those described in FIG. 1. In this example, gateway 110-xcommunicates with satellite 120-x using a feeder link 113-x which isassociated with a feeder beam 123-x having the geographical coveragearea as shown. Feeder link 113-x includes a forward uplink 114-x andreturn downlink 115-x. User terminal 130-y communicates with satellite120-y using a user link 117-y which is associated with a user beam 142-yhaving the geographical coverage area as shown. User link 117-y includesa forward downlink 118-y and a return uplink 119-y. A single userterminal 130-y is shown in this example, but a set of user terminals maybe operable within the user beam over the user link 117-y as described.

Feeder beam 123-x and user beam 142-y are partially overlapping, forminga common or overlapping geographic coverage region where the two beamsoverlap. Gateway 110-x and user terminal 130-y are positioned within thecommon coverage region provided by both the feeder beam and the userbeam. As earlier described, typical frequency reuse plans allocateseparate F/P combinations to overlapping or adjacent beams, such as whenbeams such as feeder beam 123-x and user beam 142-y overlap as shown inFIG. 5.

In FIG. 5, however, the overlapping beams are provided by differentsatellites in a manner that permits frequency reuse between devices thatcommunicate with different individual satellites. Spatial diversity isprovided between satellite 120-x and satellite 120-y. The spatialdiversity provides for spatial isolation between the satellites thatpermits both satellites to operate at a common frequency andpolarization within the overlapping geographic coverage region. A firstterminal or set of terminals include antennas that are positioned orformed for directional communication with one satellite while a secondterminal or set of terminals include antennas that are positioned orformed for directional communication with the other satellite. In thismanner, the first set of terminals may communicate with the firstsatellite using the same combination of frequency band and antennapolarization that the second set of terminals uses to communicate withthe second satellite. The spatial diversity of the satellites anddirectional antennas of the terminals permit the first satellite tocommunicate with the first set of terminals without either experiencingunacceptable levels of interference from communication between thesecond satellite and the second set of terminals. Similarly, the secondsatellite and second set of terminals will not experience unacceptablelevels of interference from the communication with the first satelliteat the same F/P combination.

In FIG. 5, gateway 110-x communicates with satellite 120-x over aforward uplink using the F/P combination designated color ‘a’ and areturn downlink using the F/P combination designated color ‘A.’ At thesame time, user terminal 130-y communicates with satellite 120-y over aforward downlink using F/P combination color ‘A’ and a return uplinkusing the F/P combination color ‘a.’ In this manner, gateway 110-x mayprovide data to satellite 120-x across forward uplink using color ‘a.’Satellite 120-x transmits the data to satellite 120-y usinginter-satellite communication link 140. Satellite 120-y receives thatdata and transmits it to user terminal 130-y across forward downlink118-y using color ‘A.’ Similarly, user terminal 130-y may provide datato satellite 120-y across return uplink 119-y using color ‘a.’ Satellite120-y transmits the data to satellite 120-x using inter-satellitecommunication link 140. Satellite 120-x receives the data and transmitsit to gateway 110-x using color ‘A.’ In another example, the forwarduplink and forward downlink may operate at the same F/P combination,while the return uplink and return downlink operate at the same F/Pcombination.

FIG. 5 shows the re-use of the F/P combination colors ‘a’ and ‘A’ by wayof example. The overlapping feeder beam and user beam may both fullyutilize any available F/P combination to the satellites. In this manner,the entire available spectrum of each satellite may be used within theoverlapping coverage area, subject only to limitations from otheradjacent beams formed with the same satellite.

Inter-satellite communication link 140 may operate at any availablefrequency. In one example, the inter-satellite communication link 140operates at the same F/P combinations allocated to the gateway and userbeams. Because of spatial diversity between the geographic coverageareas of the beams and the other satellite, the satellites maycommunicate directly using these frequencies without regard to their usefor gateway and user beams. In another example, the inter-satellitecommunication link may operate at a different frequency spectrum thanthe gateway and user beams. For example, the inter-satellitecommunication link may utilize infra-red frequencies or opticalfrequencies.

FIG. 6 is a table showing a specific example of an allocation of uniquefrequency/polarization combinations for beams associated with multiplesatellites. FIG. 6 continues with the color designations of FIG. 3A byway of example and sets forth the allocations that may be made for fourof the beams as positioned in FIG. 4. In this example, gateway beam123-2 is used for communication between a gateway and satellite 120-xover a feeder beam including a forward uplink and return downlink. Threeuser beams 142-1, 142-2, and 142-5 are used for communication betweenthree respective sets of user terminals and satellite 120-y overrespective user beams. As shown in FIG. 4, user beam 142-1, 142-2, and142-5 are each adjacent to other user beams such that they are assigneda single color downlink color and a single uplink color. User beam 142-2is allocated color A for the forward downlink and color ‘a’ for thereturn uplink. User beam 142-2 is allocated color A for the forwarddownlink and color ‘b’ for the return uplink. User beam 142-5 isallocated color C for the forward downlink and color ‘c’ for the returnuplink.

Gateway beam 123-2 is adjacent to and partially overlapping with each ofthe user beams 142-1, 142-2, and 142-5. In FIG. 4, the gateway beam isonly allocated the remaining colors d, D. Because of the spatialdiversity between satellite 120-x and satellite 120-y in FIG. 5 however,each of the F/P combinations allocated to these user beams may bere-used for gateway beam 123-2. Accordingly, gateway beam 123-2 isallocated all available F/P combinations for the feeder link. Theforward uplink is allocated colors a, b, c, and d, while the returndownlink is allocated colors A, B, C, and D. In this manner, the gatewaybeam provided by the first satellite when the user beams are provided bya second satellite can be allocated three times the capacity whencompared with the case where the gateway beam is provided by the samesatellite as the overlapping user beams.

FIG. 7 is a flowchart describing a process of allocating a commonfrequency band and antenna polarization to a feeder link and user linkin an overlapping coverage region using multiple satellites according toone embodiment. At step 302, a first satellite provides a feeder beamincluding a feeder link over a corresponding feeder beam coverage area.The feeder link may include a forward uplink for receiving data from oneor more gateways in the feeder beam coverage area and a return downlinkfor providing data to the one more gateways. At step 304, the secondsatellite provides a user beam including a user link over acorresponding user beam coverage area. The user link may include aforward downlink for transmitting data to one or more user terminals inthe user beam coverage region and a return uplink for receiving datafrom the one or more user terminals.

At step 306, a first combination of frequency band and antennapolarization is allocated to at least a portion of the feeder beam. Forexample, the first combination can be assigned to the forward uplink orthe return downlink of the feeder link. At step 308, the firstcombination is also allocated to at least a portion of the user beam.For example, the first combination can be allocated to the forwarddownlink or the return uplink of the user link. At step 310, the firstsatellite operates the feeder beam in the overlapping coverage regionusing the first combination of frequency and polarization. At the sametime, the second satellite operates the user beam in the overlappingcoverage region using the first combination. For example, the firstsatellite may receive uplink signals from the gateways at the samefrequencies used by the second satellite to receive uplink signals fromthe user terminals. Similarly, the same frequency could be used for boththe forward uplink and forward downlink instead. It is noted that thesteps of FIG. 7, and the other processes described by a flowchartherein, may be performed in any order unless otherwise specified. InFIG. 7, for example, the allocations at step 306 and step 308 may behardwired into the transponder or repeater architecture of thesatellites. The first satellite may include a bentpipe or other circuitythat operates over the common F/P combination for communication betweenthe gateway and the satellite and the second satellite may includebentpipe or other circuitry that operates over the common F/Pcombination for communication between the user terminal and thesatellite.

FIG. 8 is a flowchart describing a process of transmitting data betweena user terminal and a gateway using a common set of frequency andpolarization combinations according to one embodiment. At step 320, afirst satellite receives uplink signals from a gateway in a commoncoverage region using a first F/P combination. The first satellitetransmits a signal including the data over an inter-satellitecommunication link to a second satellite at step 322. Theinter-satellite communication link may use the samefrequency/polarization combination, but may also use differentcombinations. Moreover, the inter-satellite communication link mayoperate in a separate frequency band than the uplinks or downlinks. Forexample, the inter-satellite link may utilize infra-red or otherfrequencies, while the uplinks and downlinks use K band, Ka band, etc.frequencies. At step 324, the second satellite transmits the data in adownlink signal to one or more user terminal(s) in the common coverageregion using a second F/P combination.

At 326, the second satellite receives data from the user terminal(s) inan uplink signal using the first F/P combination. The second satellitetransmits the data to the first satellite using an inter-satellitecommunication signal at step 328. An inter-satellite link may be usedhaving a first link operating over a first frequency band fortransmission form the first satellite to the second satellite and asecond link operating over a second frequency band for transmission fromthe second satellite to the first satellite. At step 330, the secondsatellite transmits the data from the user terminal to the gateway usingthe second F/P combination. In FIG. 8, an example is presented where theuplinks both operate at one common combination of frequency band andantenna polarization and the downlinks both operate at a differentcommon combination. In another example, the forward uplink and forwarddownlink both may operate at one common combination, while the returnuplink and return downlink both operate at a different commoncombination.

FIGS. 9A-9B are simplified block diagrams of a payload architecture fora satellite in one example. FIGS. 9A-9B may be used to implement thecircuitry for a satellite such as satellite 120-x servicing a gateway ina common coverage region. FIG. 9A depicts a forward payload includingtransponder or repeater circuitry for communication from a gateway to aninter-satellite communication link with a second satellite (e.g.,satellite 120-y) and FIG. 9B depicts a return payload includingtransponder or repeater circuitry for communication from theinter-satellite communication link to the gateway. The satellite iscommunicatively coupled, via at least one feeder link antenna 402, to atleast one gateway 110 (not shown), and via at least one satellite linkantenna 408-1 to a second satellite (not shown) over an inter-satellitecommunication link. A filter or repeater path in FIG. 9A generatesinter-satellite communication signals for an inter-satellitecommunication link. The feeder link antenna may receive uplink signalsfrom the gateway using a first (or more) combination of frequency bandand antenna polarization. The received signals are amplified by one ormore low-noise amplifiers 404-1. The amplified signals are the convertedusing one or more frequency converters 406-1. Converter 406-1 maydownconvert or upconvert the amplified signals to a frequency band fortransmission over the inter-satellite link. In one example, theconverters convert a K or Ka band uplink signal to an infrared frequencyfor the inter-satellite communication link. After conversion, theconverted signals are transmitted to the second satellite usinginter-satellite communication signals over the inter-satellitecommunication link.

In FIG. 9B, SAT link antenna 408-1 receives inter-satellitecommunication signals over the inter-satellite communication link. Thesignals are amplified using one or more low-noise amplifiers 404-2. Theamplified signals are then converted using one or more frequencyconverters 406-2. Converters 406-2 may downconvert or upconvert theamplified inter-satellite communication signals to a frequency band forthe downlink to the gateway. For example, converters 406-2 may convertthe signals to a second combination of frequency band and polarization.After conversion, the signals are transmitted to the gateway usingdownlink signals over a feeder beam.

FIGS. 10A-10B are simplified block diagrams of a payload for servicinguser terminals. FIGS. 10A-10B may be used to implement the circuitry forsatellite 120-y for example. FIG. 10A depicts a forward payloadincluding transponder or repeater circuitry for communication from aninter-satellite link to a user terminal. FIG. 10B depicts a returnpayload including transponder or repeater circuitry for communicationfrom the user terminal to the inter-satellite communication link. Asatellite is communicatively coupled, via at least one SAT link antenna408-2, to a second satellite (not shown) over the inter-satellitecommunication link, and via at least one user link antenna 420 to atleast one user terminal. A filter or repeater path in FIG. 10A generatesa downlink to at least one user terminal. The SAT link antenna 408-2receives inter-satellite communication signals from another satellite.The received signals are amplified by one or more low-noise amplifiers404-3. The amplified signals are then converted using one or morefrequency converters 406-3. Converters 406-3 may downconvert orupconvert the amplified signals to a frequency band for transmission tothe user terminal. For example, converters 406-3 may convert the signalsto the second combination of frequency band and polarization. Theconverted signals are then passed to channel filters 422-1. Filters422-1 filter the signals to select user signals. After filtering, thefiltered signals are transmitted to the user terminal using user linkantenna 420.

In FIG. 10B, user link antenna 420 receives uplink signals from the userterminal, using the first combination of frequency and polarization, forexample. The signals are amplified using one or more low-noiseamplifiers 404-4. The amplified signals are passed through channelfilters 422-2 to select a bandwidth of the beam. The filtered signalsare then converted using one or more frequency converters 406-4.Converters 406-4 may downconvert or upconvert the filtered signals to aband for the inter-satellite communication link. After conversion, thesignals are transmitted to the second satellite using inter-satellitecommunication link.

In one embodiment, the individual satellites are dedicated user terminalsatellites or dedicated gateway satellites. In this manner, a singlesatellite only provides gateway beams or user beams, but not both. Theaccess functions may be segregated between satellites to enable furthersystem optimization. This may be used to improve capacity or reach backto distances between user terminals and gateways than one satellite maybe able to perform.

In another example, the individual satellites may provide feeder beamsand user beams to provide connectivity to both gateway terminals anduser terminals. FIG. 11 is a simplified block diagram describing oneembodiment including multiple satellites that operate over a commonfrequency band and antenna polarization in a common coverage area toprovide connectivity to both gateways and user terminals at bothsatellites. In FIG. 11, each satellite operates as shown in FIG. 5.Satellite 120-x provides a feeder beam including feeder link 113 thatoperates over a first set of combination of frequency and polarization(e.g., color ‘a’ uplink, color ‘A’ downlink). Satellite 120-y provides auser beam including user link 117 that operates over the first set ofF/P combinations. In FIG. 11, each satellite provides complementaryaccess services to the other satellite. In addition to feeder beam123-x, satellite 120-x provides a user beam 142-x including user link117-x. In addition to a user beam 142-y, satellite 120-y provides afeeder beam 123-y including feeder link 113-y. In this manner, gateway110-x can access satellite 120-x to provide access services to a secondset of user terminals (UT2) that access satellite 120-y. Gateway 110-xuses the same F/P combination in accessing satellite 120-x as the userterminals 120-y use in accessing satellite 120-y. In the specificexample, the feeder link is shown as operating with a forward uplink atcolor ‘a’ and a return downlink at color ‘A.’ Similarly, user link 117-yoperates with a forward downlink at color ‘A’ and a return uplink atcolor ‘a’. Other reuses of the first combination of color ‘A’ and color‘a’ for the uplinks/downlinks can be used as earlier described.

In FIG. 11, the user link 117-x at satellite 120-x operates over a thirdand fourth combination of frequency and polarization, which is reused bythe feeder link 117-y at satellite 120-y. In the specifically describedexample, feeder link 113-y includes a forward uplink 114-y that operatesover the third combination, color ‘b’, and a return downlink 115-y thatoperates over the fourth combination, color ‘B’. Similarly, user link117-x includes a return uplink 119-x that operates over the thirdcombination, color ‘b’, and a forward downlink 118-x that operates overthe fourth combination, color ‘B.’ The user links and feeder links canprovide complementary access using communication paths as earlierdescribed with respect to the gateways and user terminals. Data can bereceived at satellite 120-x from uplink 114-x from gateway 110-x usingcolor ‘a’. The data is transmitted to satellite 120-y usinginter-satellite link 140. Satellite 120-y transmits the data to thesecond user terminal 130-y over downlink signal 118-y using color ‘A.’Data can be received at satellite 120-y from uplink 119-y from thesecond user terminal 130-y using color ‘a’. The data is transmitted tosatellite 120-x using inter-satellite link 140. Satellite 120-xtransmits the data to the first gateway 110-x over downlink signal 115-xusing color ‘A.’ Likewise, data can be received at satellite 120-y overuplink 114-y from gateway 110-y using color ‘b’. The data is transmittedto satellite 120-x using inter-satellite link 140. Satellite 120-xtransmits the data to the first user terminal 130-x over downlink signal118-x using color ‘B.’ Data can be received at satellite 120-x fromuplink 119-x from the first user terminal 130-x using color ‘b’. Thedata is transmitted to satellite 120-y using inter-satellite link 140.Satellite 120-y transmits the data to the second gateway 110-y overdownlink 115-x using color ‘B.’

In FIG. 11, the available bandwidth to each satellite is divided betweenthe user links and feeder links. Nevertheless, the feeder link F/Pcombination at satellite 120-x is reused by the user link at satellite120-y and the user link F/P combination at satellite 120-x is reused bythe feeder link at satellite 120-y within the common coverage area. Inthis manner, each satellite is able to fully utilize the availablebandwidth within the common coverage area without experiencing orproviding interference due to spatial diversity between the satellites.

FIG. 12 is a flowchart describing a process of reusing frequencies in amulti-satellite system that employs feeder and user links at eachsatellite. At step 340, a first satellite provides a first feeder beamand a first user beam associated with a common geographical coverageregion. At step 342, a second satellite provides a second feeder beamand a second user beam that are both associated with the commongeographical coverage region. At step 344, a first set of F/Pcombinations is allocated to the first feeder beam and at step 346, asecond set of F/P combinations is allocated to the first user beam.Within the feeder and user beams, two combinations of frequency andpolarization may be used for the uplinks and downlinks as has beendescribed. At step 348, the first set of F/P combinations is allocatedto the second user beam and at step 350, the second set of F/Pcombinations is allocated to the second feeder beam.

At step 352, the first satellite operates the first feeder beamsimultaneously while the second satellite operates the second user beam.Both satellites operate the respective beams using the first set of F/Pcombinations allocated at steps 344 and 348. At the same time that step352 is performed, the first satellite operates the first user beamsimultaneously while the second satellite operates the second feederbeam at step 354. Both satellites operate the respective beams using thesecond set of F/P combinations allocated at steps 346 and 350. In thismanner, each satellite divides its available bandwidth between thefeeder beam and user beam. The frequencies are reused between the twosatellites within the common coverage region to provide a capacity equalto the sum of the capacity of the individual satellites.

FIG. 13 is a flowchart describing a process of transmitting data betweena first gateway and a second set of user terminals using a first set offrequency and polarization combinations, while transmitting data betweena second gateway and a first set of user terminals using a second set offrequency and polarization combinations. The first gateway and first setof user terminals communicate with a first satellite, while the secondgateway and the second set of user terminals communicate with a secondsatellite. Inter-satellite communication links are used to transmit databetween the first gateway and the second set of user terminals, andbetween the second gateway and the first set of user terminals. Theprocess of FIG. 13 includes the process outlined in FIG. 8.Specifically, a first F/P combination is used to transmit data in anuplink between the first satellite and the first gateway (step 320). Thedata is transmitted to the second satellite in using an inter-satellitecommunication link (step 322). The second satellite transmits the datain a downlink to the second user terminal using a second F/P combination(step 324). Data is also received from the second user terminal usingthe first F/P combination (step 326). The data is transmitted to thefirst satellite using the inter-satellite communication link (step 328).The first satellite transmits the data in a downlink to the firstgateway using the second F/P combination (step 330).

In addition to the process described in FIG. 8, the process of FIG. 13includes providing data between the first set of user terminals thatcommunicate with the first satellite and the second gateway thatcommunicates with the second satellite. At step 360, the secondsatellite receives uplink signals from the second gateway in the commoncoverage region using a third F/P combination. The second satellitetransmits a signal including the data over an inter-satellitecommunication link to the first satellite at step 362. At step 364, thefirst satellite transmits the data in a downlink signal to a first userterminal or set of user terminals in the common coverage area using afourth F/P combination.

At 366, the first satellite receives data from the first userterminal(s) in an uplink signal using the third F/P combination. Thefirst satellite transmits the data to the second satellite using aninter-satellite communication signal at step 368. At step 370, thesecond satellite transmits the data from the first user terminal to thesecond gateway using the fourth F/P combination. In FIG. 13, an exampleis presented where the uplinks between a first gateway and first userterminal both operate at one common combination of frequency band andantenna polarization and the downlinks both operate at a differentcommon combination. In another example, the forward uplink and forwarddownlink both may operate at one common combination, while the returnuplink and return downlink both operate at a different commoncombination. Similarly, the forward uplink and forward downlink betweenthe second gateway and the first user terminal may operate at the thirdcombination, while the return uplink and return downlink both operate atthe fourth combination.

FIG. 14 is a simplified block diagram describing one embodimentincluding multiple satellites that operate over a common frequency bandand antenna polarization in a common coverage area. In FIG. 14, anexample is described whereby two user terminals in a common coverageregion communicate across an inter-satellite link using a commonfrequency band and antenna polarization for communication withrespective satellites. Satellite 120-x provides a user beam 142-xincluding a user link 117-x that operates over a first set ofcombination of frequency and polarization (color ‘a’ uplink, color ‘A’downlink). Satellite 120-y provides a second user beam 142-y including auser link 117-y that operates over the first set of F/P combinations. Inthe specific example, the first user link 117-x is shown as operatingwith a forward uplink at color ‘a’ and a return downlink at color ‘A.’Similarly, user link 117-y operates with a forward downlink at color ‘A’and a return uplink at color ‘a’. Other reuses of a combination offrequency band and antenna polarization can be used as earlierdescribed.

In FIG. 14, direct bi-directional communication between the two userterminals may be established using a common F/P combination in thecommon coverage area. Satellite 120-x can receive data in an uplink119-x over user link 117-x at a first F/P combination (e.g., color ‘a’).Satellite 120-x transmits the data to satellite 120-b usinginter-satellite communication link 140. Satellite 120-y transmits thedata to user terminal 110-y over downlink 118-y of user link 117-y at asecond F/P combination (color ‘A’). Simultaneously, satellite 120-y mayreceive data in an uplink 119-y of user link 117-y at the first F/Pcombination. Satellite 120-y transmits the data to satellite 120-x usinginter-satellite communication link 140. Satellite 120-x transmits thedata to user terminal 110-x over downlink 118-x of user link 117-x. Inone embodiment, each satellite includes a router or channel-switchingcapability to allow user terminal to user terminal connectivity withhigh bandwidth. In FIG. 14, each user terminal uses the same F/Pcombination for the uplink signals and the same F/P combination for thedownlink signals. In another example, one user terminal may use thefirst combination for the uplink signals and the second combination forthe downlink signals, while another user terminal uses the firstcombination for the downlink signals and the second combination for theuplink signals.

Accordingly, there has been described a method of satellitecommunication that includes providing a feeder beam at a first satelliteusing a first combination of frequency band and antenna polarization,transmitting from the first satellite to a second satellite a first setof inter-satellite communication signals based on first data receivedfrom the feeder beam, providing a service beam at the second satelliteusing the first combination of frequency band and antenna polarization.A second combination of frequency band and antenna polarization is usedto transmit from the second satellite to the first satellite a secondset of inter-satellite communication signals based on second datareceived from the service beam. The feeder beam is associated with afeeder beam coverage area and the service beam is associated with aservice beam coverage area that is at least partially overlapping withthe feeder beam coverage area.

A wireless communication system has been described that includes a firstsatellite configured to provide a feeder beam over a feeder beamcoverage area using a first combination of frequency band and antennapolarization, and a second satellite configured to provide a servicebeam over a service beam coverage area using the first combination offrequency band and antenna polarization. The first satellite isconfigured to transmit to a second satellite a first inter-satellitecommunication signal based on first data received from the feeder beam.The second satellite is configured to transmit to the first satellite asecond inter-satellite communication signal based on second datareceived from the service beam. The service beam coverage area is atleast partially overlapping with the feeder beam coverage area.

A wireless communication system has been described that includes a firstsatellite having one or more first repeaters including an inputconfigured to receive first data in a first set of uplink signals of afeeder beam using a first combination of frequency band and antennapolarization and a second satellite having one or more second repeatersincluding an input configured to receive second data in a second set ofuplink signals of a service beam using the first combination offrequency band and antenna polarization. The feeder beam has a feederbeam coverage area. The one or more repeaters have an output configuredto transmit to the second satellite a first set of inter-satellitecommunication signals based on the first data received from the feederbeam. The service beam has a user beam coverage area that is at leastpartially overlapping with the feeder beam coverage area. The one ormore second repeaters have an output configured to transmit to the firstsatellite a second set of inter-satellite communication signals based onthe second data received from the service beam.

A method of satellite communication has been described that includesreceiving first data at a first satellite from a feeder beam using afirst combination of frequency band and antenna polarization,transmitting the first data from the first satellite to a secondsatellite using a first inter-satellite communication link. The secondsatellite receives the second data from a user beam using the firstcombination of frequency band and antenna polarization, and transmittingthe second data from the second satellite to the first satellite using asecond inter-satellite communication link. The feeder beam has a feederbeam coverage area. The user beam has a user beam coverage area that isat least partially overlapping with the feeder beam coverage area.

A method of satellite communication has been described that includesproviding a first user beam at a first satellite using a firstcombination of frequency band and antenna polarization, transmittingfrom the first satellite to a second satellite a first set ofinter-satellite communication signals based on data received from thefirst user beam, providing a second user beam at the second satelliteusing the first combination of frequency band and antenna polarization,and transmitting from the second satellite to the first satellite asecond set of inter-satellite communication signals based on datareceived from the second user beam the second user beam. The feeder beamand the user beam include a common coverage region.

A method of satellite communication has been described that includesreceiving at a first satellite a first uplink signal from a firstgateway using a first combination of frequency band and antennapolarization. The first gateway is located in a common coverage regioncorresponding to a first gateway beam for the first satellite and afirst user beam for a second satellite. The method includes transmittingfrom the first satellite to the second satellite a first inter-satellitecommunication signal based on the first uplink signal, and transmittingfrom the second satellite to a first user terminal a first downlinksignal based on the inter-satellite communication signal. The firstdownlink signal uses a second combination of frequency band and antennapolarization, and the first user terminal is located in the commoncoverage region corresponding to the first user beam for the secondsatellite. The method includes receiving at the second satellite asecond uplink signal from the first user terminal using the firstcombination of frequency band and antenna polarization, transmittingfrom the second satellite to the first satellite a secondinter-satellite communication signal based on the second uplink signal,and transmitting from the first satellite to the first gateway a seconddownlink signal based on the second inter-satellite communicationsignal. The second downlink signal utilizing the second combination offrequency band and antenna polarization.

A method of satellite communication has been described that includesreceiving at a first satellite a first uplink signal from a first userterminal using a first combination of frequency band and antennapolarization. The first user terminal is located in a common coveragearea corresponding to a first user beam for the first satellite and asecond user beam for a second satellite. The method includestransmitting from the first satellite to the second satellite a firstinter-satellite communication signal based on the first uplink signal,and transmitting from the second satellite to a second user terminal afirst downlink signal based on the inter-satellite communication signal.The first downlink signal utilizes a second combination of frequencyband and antenna polarization, and the second user terminal is locatedin the common coverage area corresponding to the second user beam forthe second satellite. The method includes receiving at the secondsatellite a second uplink signal from the second user terminal using thefirst combination of frequency band and antenna polarization,transmitting from the second satellite to the first satellite a secondinter-satellite communication signal based on the second uplink signal,and transmitting from the first satellite to the first user terminal asecond downlink signal using the second combination of frequency bandand antenna polarization.

A method of satellite communication has been described that includesreceiving data at a first satellite from a feeder beam using a firstcombination of frequency band and antenna polarization, the feeder beamhaving a feeder beam coverage area, transmitting the data from the firstsatellite to a second satellite using an inter-satellite communicationlink, and providing the data from the second satellite in a user beamusing the first combination of frequency band and antenna polarization.The user beam has a user beam coverage area that is at least partiallyoverlapping with the feeder beam coverage area.

The foregoing detailed description has been presented for purposes ofillustration and description. It is not intended to be exhaustive or tolimit the subject matter claimed herein to the precise form(s)disclosed. Many modifications and variations are possible in light ofthe above teachings. The described embodiments were chosen in order tobest explain the principles of the disclosed technology and itspractical application to thereby enable others skilled in the art tobest utilize the technology in various embodiments and with variousmodifications as are suited to the particular use contemplated. It isintended that the scope of the invention be defined by the claimsappended hereto.

What is claimed is:
 1. A method of satellite communication, comprising:receiving first data at a first satellite from a feeder beam using afirst combination of frequency band and antenna polarization, the feederbeam having a feeder beam coverage area; transmitting the first datafrom the first satellite to a second satellite using a firstinter-satellite communication link; receiving second data at the secondsatellite from a user beam using the first combination of frequency bandand antenna polarization, the user beam having a user beam coverage areathat is at least partially overlapping with the feeder beam coveragearea; and transmitting the second data from the second satellite to thefirst satellite using a second inter-satellite communication link. 2.The method of claim 1, further comprising: transmitting the second datafrom the first satellite to a gateway in an overlapping region of thefeeder beam coverage area and the user beam coverage area using a secondcombination of frequency band and antenna polarization; and transmittingthe first data from the second satellite to a user terminal in theoverlapping region using the second combination of frequency band andantenna polarization.
 3. The method of claim 2, wherein the feeder beamis a first feeder beam, the gateway is a first gateway, the user beam isa second user beam, and the user terminal is a second user terminal, themethod further comprising: receiving third data at the first satellitefrom a first user terminal in the overlapping region using a first userbeam at a third combination of frequency band and antenna polarization,the first user beam covering the overlapping region; transmitting thethird data from the first satellite to the second satellite using athird inter-satellite communication link; and receiving fourth data atthe second satellite from a second gateway using a second feeder beam atthe third combination of frequency band and antenna polarization, thesecond feeder beam covering the overlapping region.
 4. The method ofclaim 3, further comprising: transmitting the fourth data from the firstsatellite to the first user terminal in the overlapping region using afourth combination of frequency band and antenna polarization; andtransmitting the third data from the second satellite to the secondgateway using the fourth combination of frequency band and antennapolarization.
 5. A method of satellite communication, comprising: at afirst satellite, providing a first user beam using a first combinationof frequency band and antenna polarization, the feeder beam isassociated with a common coverage region; transmitting from the firstsatellite to a second satellite a first set of inter-satellitecommunication signals based on data received from the first user beam;at the second satellite, providing a second user beam using the firstcombination of frequency band and antenna polarization, the second userbeam beam is associated with the common coverage region; andtransmitting from the second satellite to the first satellite a secondset of inter-satellite communication signals based on data received fromthe second user beam.
 6. The method of claim 5, wherein: providing thefirst user beam comprises receiving at the first satellite a firstuplink signal including first data from a first user terminal using thefirst combination of frequency band and antenna polarization, the firstuser terminal is located in the common coverage region; transmitting thefirst set of inter-satellite communication signals includes transmittinga first inter-satellite communication signal including the first data;and providing the second user beam comprises transmitting to a seconduser terminal a first downlink signal including the first data using asecond combination of frequency band and antenna polarization, thesecond user terminal is located in the common coverage region.
 7. Themethod of claim 6, wherein: providing the second user beam comprisesreceiving at the second satellite a second uplink signal includingsecond data from the second user terminal using the first combination offrequency band and antenna polarization; transmitting the second set ofinter-satellite communication signals includes transmitting a secondinter-satellite communication signal including the second data; andproviding the first user beam comprises transmitting to the first userterminal a second downlink signal including the second data using thesecond combination of frequency band and antenna polarization.